Method and apparatus for bending tubular glass articles



Jan. 17, 1950 Filed Jan. 26, 1945 A. GREINER ET AL 2,494,872 METHOD AND APPARATUS FOR BENDING TUBULAR GLASS ARTICLES 9 Sheets-Sheet l Inventors:

Alfred Gr-einer, August W. Seibz,

Mt -W Their Attorney.

Jane 17, 1950 A. GREINER ET AL METHOD AND APPARATUS FOR smmamc TUBULAR GLASS ARTICLES 9 Shets-Sheet 2 Filed Jan; 26, 1945 WW ..2 WA sew n rn w 2 065 H *mwfi Nu e am w w m mg h a) u T a a AA w a w w 1% x w w u W W 2. w w w M n H a. C :t. E, WAR m M a a 2 F m Jan. 17, 1950 A. GREINER ETAL 2,494,372

METHOD AND APPARATUS FOR BENDING TUBULAR GLASS ARTICLES Filed Jam 26, 1945 9 Sheets-Sheet 5 Inventors:

Alfred Greiner, August W. SEHLZ,

L Their- Attorneg.

Jan 17, 1950 A. GREINER ETAL 2,494,872

METHOD AND APPARATUS FOR BENDING TUBULAR GLASS ARTICLES Filed Jan. 26. 1945 9 Sheets-Sheet 4 /7- flnventors:

AIR-ed Greiner, August W. seitz,

Their- Attorney.

Jan. 177, 1950 A. GREINER METHOD AND APP ET AL 2,494,872 ARATUS FOR BENDING TUBULAR GLASS ARTICLES Filed Jah. 26, 1945 9 Sheets-Sheet 6 Inventors:

Alfred Greiner, Augus t W. Seibz,

/Z3 illlllllllllilhl.

Jan. 17, 1950 A. GREINER ETAL 2,494,872

METHOD AND APPARATUS FOR BENDING TUBULAR GLASS ARTICLES Filed. Jan. 26, 1945 9 Sheets-Sheet 7 NIT/Q0651?! L 7 Vi J5.

L/A/f l :1 j 3: Invenb T-s: Alfred Gremer,

(1/ Their Attorney.

Patented Jan. 17, 1950 2,494,872 METHUD AND APPARATUS on BENDING TUBULAR GLAss n'rIoLEs Alfred Greiner, Cleveland Heights, and August W Seitz, Euclid, Ohio, assig'n'ors to General Electric Company, a corporation of New York Application was 26, 1945, Serial No. 574,724

Our invention relates, in general, to method and apparatus for bending glass tubing into arcuate or circular shape, and more particularly to method and apparatus for bending tubular electric lamps or dischargedevices, such as fluorescent lamps, into circular shape. l

One object of our invention is to provide a method and apparatus for bending tubular glass articles into true arcuate or circular shape while maintaining the cross-sectional shape thereof.

Another object of our invention is to provide a method andappara'tus for bending theglass envelope assembly of a tubular electric lamp into true arcuate or circularshape while maintaining the cross-sectional shape thereof. 1

Still another object of our invention is to provide a method and apparatus for bending the glass envelope assemblies of tubular electric lamps into true arcuately or circularly shaped'envelopes of substantially uniform arcuate extent.

Further objects and advantages of our invention will appear from the following description of a species thereof and from the accompanying drawings in which:

Fig. l is a side elevation of apparatus comprising our invention; Fig. '2 is a vertical sectionyon the line 22 of Fig. 1, showing the envelope supporting and heating means of the apparatus shown in 1; Fig. 3 is' a fragmentary-vertical section, on the line B -3 of Fig. l -showing in elevation the upper holder for the tubular lamp envelope assembly; Fig. 4 is a horizontal section on the line 5- 3 of Fig. 3; Fig. 5 is a vertical section on the line 5-5 of Fig. i; Fig. 6 is a fragmentary vertical section on the line 5-5 of Fig. 1 and showing the lower holder for the lamp envelope assembly; Fig. '7 is a vertical section, on the line i-'l of Fig. 1, showing the drum assembly carriage of the apparatus comprising our invention; Fig. 8 is a horizontal section on the line 8-3 of Fig. 1 but with the drum assembly carriage shown in its forward or operative position; Fig. 9 is a vertical section on the line 9 9 of Fig. 8; Fig. 10 is avertical section on the line iii-23 of Fig. 8; Fig. 11 is a fragmentary perspective view of the envelope back support and associated operating mechanism therefor; Fig. 12 is a diagram of the control circuit of the electric motor for raising and lowering the drum lift carriage; 13 is a diagrammatic illustration of the control mechanism for regulating the flow of inert gas to the lamp envelope; Fig. 14 is a fragmentary vertical section of a modified drum assembly carriage; Fig. 15 is a fragmentary plan view of the modified drum disc control means 30 Claims.

shown in Fig. 14; Fig. 16 is a plan view of a modified furnace arrangement; and Fig. 17 is a vertical se'cti'o'n onthe 1ine"il-l1 of Fig. 16.

In accordance with the invention, the tubular glass envelope" assemblywhichis' to be bent is first heated'to'a temperature" at which it is readily deformable and at which it attains-"a; predetermined elongationywhereupon'one end of theenvelope' is attached to the periphery-oi a rotatable drum 'and the drum then rolled along the em velo'pe to cause the" envelope to bebentor wrapped around the drumpe'riph'ery. v l The drawings illustrate one embodiment of apparatusaccording to the invention for bending into circular shape atubul'ar electric lamp env'elope' assembly I, for example; afluorescent lamp of the general type in commonuse at present.- The "said lamppnvelope assembly I com"- prises a tubular glass envelope 2 having anelectrode mount 3' (Fig; 6)rsealed into each end thereof as well as exhaust tubes 4 and 5 extending longitudinally from the opposite ends-of the envelope. The exhaust cubed at one end of the envelope 2 extends axially thereof while the other exhausttube is offset a sufiicient distance relative to the envelope axis to clear theenvel'ope end carrying the tube l, during the final stages of the envelope bending operations The 'axial exhaust tube 4 ispartially closed at its outer end 'topro .videa constricted opening 6 (Fig.6) for retarding the outward flow of the inert gas, suclr'a's nitrogen; which is introduced into the envelope through the other exhaust tube 5 during theb'endjing -'operation; Inthe particular form of lamp illustrated the opposite ends of the envelope' z are further provided with metal end caps-m1 which may be made of chrome iron and-fusion sealed directly to the glass of the-envelope.- The said endcaps l areeach formed with a-centrally located outwardly projecting boss'8 the annular side Wallfi of which is relieved or tapered inwardly to thereby form a constriction or reduced diameter portion H1 at the base of the boss. 'The top wall of the boss 8 is provided with a central aperture ll of circular form through which project't-he exhaust tubes 4, 5 and the lamp leading-in wires l2, l3.

"The apparatus according to the invention for bending the envelope assembly I into circular shape comprises upper and lower vertically aligned holders M and [5, respectively, forvertically supporting the said envelope assembly at its opposite ends, with the offset exhaust tube "5 uppermost. The upper holder [4 is 'supported'on' a irameworklfi which e'xtendsupward froma 3 table or base El and consists of a pair of upstanding side bars or angle irons l8, l8 fastened to the table H and bridged at their upper ends by a cross bar 59. The upper holder I4 is secured to the cross bar H3 at a point midway between the frame side bars it.

As shown particularly in Figs. 3 to 5, the upper holder l4 comprises an L-shaped support bracket 28 fastened to and depending from the cross bar l9 and having a pair of legs 2!, 2i extending horizontally from its lower end and spaced apart to thereby provide a passageway therebetween for the accommodation of the upwardly extending lamp exhaust tube 5. The two legs 2| of the bracket 26 carry a pair of depending rods 22, 22 to the lower extremity of which is fastened a lamp carrier jaw 23 having a U-shaped recess 24 for receiving the metal end cap 7 on the upper end of the lamp envelope 2. The upper edge of the recess 24 in the carrier jaw 23 is beveled, as indicated at 25 in Fig. 5, to thereby provide a seat on which the flaring side wall a of the lamp end cap l is adapted to rest to thereby support the lamp envelope assembly I.

Suitable locking means are provided on the carrier jaw 23 for locking the lamp end cap 1 in place within the recess 24 after it has been inserted to the limit of its movement thereinto. In the particular case illustrated, the said looking means comprises a horizontally swinging latch bar or gate 25 pivoted on one of the arms El of the carrier jaw 23. In its closed or locked position, the latch bar 26 extends across the outer ends of the carrier jaw arms 27 and 28 so as to bridge the Open end of the recess 24, the latch bar 25 being provided with a centrally located depending tongue 29 which projects down beyond the top of theboss 3 on the end cap 1 positioned in the carrier jaw 23 to thereby prevent any movement of the end cap outwardly of the recess 24. To look the latch bar 26 in its closed position, the free end of the bar is provided with a small depending lug .38 which is inserted in an aperture 3i in the arm 28 of the carrier jaw 23 after the latch bar has been swung to its closed position. The latch bar 26 is loosely pivoted in the carrier jaw arm 2'! so as to be capable of a limited amount of vertical swinging movement at least sunicient to enable the free end of the bar 26 to be swung over the top of the arm 28 and i the lug 38 inserted in the aperture 3|.

The upper holder i4 is further provided with holding means for the offset exhaust tube 5 of the lamp, the said holding means comprising a small block 32 secured to the holder bracket 26 and having a vertically extending V-notch 33 in its front face for receiving the exhaust tube 5 therein. The said exhaust tube 5 is held within the V-notch 33 by means of a cooperating pair of spring-pressed horizontally pivoted jaws 34 which are pivotally mounted in the block 32 within a horizontal slot 35 therein. The jaws 34 are pressed against the exhaust tube 5 by plate springs 35 secured at one end to the sides of the block 32 and having their free ends bearing against the jaws 34. The facing edges of the spring-pressed jaws 34 are formed with tapered tube-engaging portions 31 which converge towards the free or outer ends of the jaws so as to continuously urge and press the exhaust tube 5 back against the walls of the V-notch 33.

The lower holder 5 5 for the envelope assembly 1 comprises a vertically reciprocable rod 38 mounted in a vertical sleeve bearing 39 fastened to the upper side of the table top 46. The upper end of the rod 38 carries a short arm 4| provided with an annular seat 42 (Fig. 6) which is adapted to engage the end wall of the cap I on the lower end of the envelope 2. The said arm 4| is further provided with an upstanding frustro-conical boss 43 concentric with the seat 42 and adapted to be inserted into the opening I I in the lower lamp end cap 7 to thereby center and hold the lower end of the envelope assembly in place, thus maintaining the vertical positioning of the envelope assembly. The arm 4! is further provided with a vertical bore 44, concentric with the seat 42 and boss 43, for the accommodation of the lamp exhaust tube 4 and the leading-in wires l2, I3.

Upon being mountedin place in the holders [4 and i5, the envelope assembly is heated in an oven 45 to a temperature at which it first becomes readily deformable, During this heating operation, however, the envelope 2 tends to elongate to a certain degree. To permit the free elongation of the envelope, the lower holder I5 is provided with suitable floating support means 46 (Fig. 1) for enabling the said holder to float in any given vertical position within the limits of its vertical reciprocating movements. As a result, the lower holder l5 offers practically no resistance at all to the elongation of the envelope 2, the latter merely pushing down the lower holder l5 as it elongates. The said floating support means it comprises a more or less horizontally disposed counterweighted lever 47 pivotally mounted intermediate its ends on a depending bracket 48 secured to the underside of the table top 46. One arm of the lever 41 carries a suitable counterweight 49 while the other arm is connected by a vertical link 5E1 to the lower end of the holder rod 38 which projects down through an opening 5! in the table top 40.

The oven 45 for heating the lamp envelope 2 may be in the form of an elongated electric furnaCe which is of sufhcient length to completely receive the lamp envelope 2 therein and which will heat the envelope substantially uniformly throughout its entire length. The furnace 45 is maintained at a temperature slightly above the temperature at which the glass lamp envelope 2 becomes readily deformable. In the case of a soft lead-glass envelope for instance, the temperature of the furnace will be around 700 to 800 C. or thereabouts. To prevent cracking of the glass envelope 2 upon being subjected to the high temperature of the furnace 45, the envelope 2 is preferably preheated prior to its insertion in the furnace.

As shown in Figs. 1 and 2, the furnace 45 is supported in a vertical position on a carrier or carriage 52 which rides on a horizontal track 53. The said track 53 is mounted on the upper side of the table top 46 and extends through, and normal to the plane of, the supporting framework l6 for the upper lamp holder 14. The furnace 45 is vertically divided into a stationary rear section '54 and a swinging front section 55 which may be swung open to allow the introduction of the lamp envelope 2 into the furnace. The upper and lower end walls of the furnace 45 are provided with suitable openings for the accommodation, respectively, of the upper lamp exhaust tube 5 and upper holder rods 22, and the lower holder support rod 3%. At its upper end the furnace 45 is provided with a spaced pair of rollers 56 rotating on vertical axes and arranged to engage a cooperating pair of spaced guide bars 5'. fastened to the underside of the frame cross bar 19 to thereby guide and additionally support the upper end of the furnace.

The enclosure of the" lamp envelope 2 within the furnace at is accomplished by first swinging open the front furnace section 55 by means of a handle 58 thereon, and then advancing the fur nace carriage 52 along the track 53 until the furnace is located in its envelope heating posi-- tion as determined by the engagement of the carriage 52 with stops 59 on the track 53. This advancing movement of the carriage 52 along the track, as well as the subsequent retracting movement thereof, may be eifected by suitable automatic means, such as by an air cylinder A (Figs. 16 and 1'7) the piston of which is connected to the carriage 52 by a connecting rod 52. With the furnace 45 thus advanced to its envelope heating position, the front section 55 of the furnace is then swung to its closed position to thereby complete the enclosing of the lamp envelope 2 within the furnace. During the heating of the envelope 2 in the furnace 45, and also during the ensuing bending operation, nitrogen or other suitable inert gas such as argon, forming gas (which is a mixture of nitrogen and hydrogen), etc., is introduced intothe envelope 2, through a rubber tube 66 connected to the exhaust tube 5, to prevent heat deteriorationof the fluorescent powder coating on the inner surface of the envelope wall as Well as to prevent oxidation of the metal parts of the lamp electrodes.

The heating of the lampenvelope 2 in the furnace 45, with consequent elongation of the envelope, continues until the envelope attains a temperature at which it just becomes deformable and capable of being bent. At this temperature, the envelope 2 will have elongated a predetermined amount.

In accordance with the invention, suitable means are employed for providing an indication of when the envelope has attained such a predetermined elongation and therefore possesses the necessary temperature for bending, the said indicating means comprising a collar 6!, on the lower holder support rod 33 and a limiting stop 62 therefor in the form of a horizontally reciprocable slide bar having a forked end 53 partially surrounding the rod 38 and underlying the collar 6| so as to be engaged thereby. The bar 82 is slidably mounted in a slide block. 54 (Fig. .2) supported on an upstanding standard 65 mounted on the table top ill, whereby the said slide bar may be withdrawn out from under. the collar 8| on rod 38 to thereby permit further downward movement of the lower holder l5.

In addition to providing an indication of when the envelope 2 has attained the required elongation and therefore the required bending temperature, the engagement of the collar 6| with the slide bar 52 (as shown in dotted lines at El in Fig. 2) also serves to limit further elongation of the lamp envelope. In this manner, the various individual lamp envelope assemblies l, which are to be bent, will all possess the same overall length at the outset of the bending operation and therefore will possess uniform circular length at the completion of the bending operation.

When the envelope 2 has been heated to proper bending temperature, as indicated bythe engage ment of the stop. by the collar 6| on the lower holder rod 38, the envelope assembly I is Withdrawn from the furnace 45, an envelope back support 56 immediately brought into engagement with or closely adjacent the envelope 2, and the lower end of the envelope immediately clamped to the periphery of a forming mold or drum 61 rotatable about a horizontal axis, which drum is then moved bodily upward and simultaneously rotated about its axis to thereby wrap the envelope 2 around the periphery of the drum. The withdrawal of the envelope assembly I from the furnace 45 is effected by first swinging the front section 55 of the furnace to its open position, and then moving the furnace carriage 52 back wards a sufficient distance to be out of the way during the subsequent operation of the apparatus.

The winding drum or form 67 is supported in a vertically movable lift carriage 83 which, in turn, is carried on a horizontally movable drum assembly carriage or carrier 69 riding on the track 53. The drum assembly carriagefiQ is provided with a pair of upstanding parallel guide columns (d which are spaced apart laterally of the carriage track 53 and on which the lift carriage 68 is slidably mounted for vertical movement therealong. The upper end of the vertical guide columns 1c are secured to the cross-bar member H of an upstanding framework supported on the carriage 68 and comprising a pair of side bars 12 (Fig. 7) bridged at their upper ends by the said cross-bar H.

The drum lift carriage 58 comprises a horizontally disposed U-shaped frame or yoke 13 slidably mounted on the guide columns H1 and carrying the drum fi'l between the two arms 14 of the U-frame. The said frame arms M are provided with vertically extending sleeve bushings 1 5 which have a sliding fit on the guide columns 10 to thus support the frame 13 in its horizontal position.

The drum or form assembly 6'! on which the envelope 2 is wound comprises duplicate corresponding parts which have been given the same reference numeral, including a pair of facing discs 16 which are axially separable relative to one another and which are mounted on individual horizontally disposed shafts 11 extending transversely of the track 53 and journalled in the arms 14 of the carriage frame 13. The discs 15 are fastened at their outer sides to flanges 18 on hubs or collars 19 which are mounted on and fixedly secured to the shafts ll, as by set screws for in stance. The peripheries of the discs 16 are an- .nularly recessed or grooved at the inner, facesof the discs to provide identical complementary annular groove portions 8B which, when the two discs 16 are brought together into face to face abutting engagement, conjointly form an annular envelope-receiving groove or channel 8| conforming to the cross-sectional shape of the envelope 2. The peripheries of the two discs 15, including the grooved portions thereof, are preferably covered with asbestos 82 or other suitable heat insulating material to thereby prevent cracking of the heated glass envelope 2 upon contact with the reshaping drum 61. To further insure against such cracking of the heated glass envelope, the drum El, during use of the apparatus, may be maintained in a heated condition by suitable means, such as by gas fires from a pair of burners 51 located beneath and outwardly of the drum discs 15 and mounted onthe carriage 69 to direct the gasiires angularly upward and inward against the drum discs when the drum E1 is in its lowered or starting position.

Suitable control means 83 are provided on the drum lift carriage 68 for moving the two discs 16 axially towards and away from each other, as desired, to thereby either close or separate the two halves of the drum. As shown particularly in Figs. 8 to 10, the said disc control means 83 comprises a pair of levers 84 extending alongside the drum discs I6 outwardly thereof, and pivoted intermediate their ends on the yoke arms I l for pivotal movement in a horizontal plane. The levers 84 are provided with yoked forward ends 85 which span the collars l9 fastened to the discs I6 and carry opposed rollers 96 which ride in annular grooves 81 in the said collars I9. Pivotal movement of the levers 84 to open and close the drum discs 76 is effected by a toggle mechanism comprising a pair of toggle links 89 pivotally connected at one end to the rear ends of the respective levers 84. At their other ends, the toggle links 88 are pivotally connected by a pin 89 to a slide member 90 which is slidably mounted in a guideway 9I formed partly in the cross arm 92 of the carriage frame it and partly in one arm 93 of a U-shaped bracket 94 fastened to the back side of the frame cross arm 92. The guideway 9! extends horizontally in a direction normal to the axis of rotation of the envelope reshaping drum 61. Sliding movement of the slide 99 in its guideway 9|, to thereby pivot the levers 84 and so open or close the drum discs i9, is effected by a bell crank lever 95 pivoted at its apex on the other arm 96 of the bracket 94. One arm 97 of the bell crank lever 95 is pivotally connected to the slide 90 by a pin and slot arrangement, the slide 90 carrying a pivot pin 93 which fits within a slot 99 in the end of the lever arm 9i. The other arm I of the bell crank lever 95 serves as a handle for operating the same.

In their closed position, the drum discs I are held in spring-pressed face to face interengagement by a pair of tension coil springs iliI anchored at one end to the base of the slide bracket 94 and connected at their other ends to the arm 91 of the bell crank lever 95. The drum discs, however, are normally held in an axially separated position, against the force of the springs "H, by means of a catch I92 in the form of a and 10, the said holder I9 3 comprises a pair of complementary facing semicircular jaws I05 mounted on the discs 76 in positions transversely -of and concentrically within the grooved portions '80 of their respective discs, with the open ends of the jaws facing and aligned with one another so :as to form, when the jaws are brought together, a complete ring for encircling the lower end cap "I of the envelope. The walls I99 of the jaw openings are suitably bevelled to enable the opposing jaws I95 to enter the restriction It at the base of the end cap boss 8 and firmly grip the said end cap therebetween, thus preventing the end cap I from being pulled out of the holder I94. The jaws I05 are supported in suitable adjustable mountings I07 which provide a limited amount of adjustment for the jaws. The said mountings l m comprise jaw holder slides I08 which are slidably mounted in holder blocks I 99 for adjusting movement radially of the discs It. The holder blocks I09 are fastened to the drum discs I6 and ride in 8 annular grooves I I0 in the outer side faces of the said discs IE to permit adjustment of the jaws I05 to any desired position around the periphery of the drum discs H5.

The drum lift carriage 68 is normally located in a lowered or starting position (as shown in Fig. 1) wherein the envelope gripping jaws I05 on the drum discs 76 are horizontally aligned with, and in proper gripping relation to the lower end cap I of the lamp envelope 2 when the latter has been heated to its proper bending temperature and has elongated to its predetermined length as determined by the engagement of the lower holder collar 6| with the limiting stop 62. The drum lift carriage 99 is supported in its said lowered position by the engagement of the lower ends of the carriage frame bushings with suitable stops I I I secured to the guide columns 10.

The clamping of the lower end of the heated lamp envelope 2 to the periphery of the drum 61 is accomplished by first advancing the drum assembly carriage 69 along the track 53 to its forward or operative position (as determined by its engagement with stops I I2 on the track) wherein the envelope gripping jaws I05 on the drum discs I6 are positioned abreast of the lower end cap I of the lamp envelope. As in the case of the furnace carriage 52, the advancing movement of the carriage 69 along the track, as well as the subsequent retracting movement thereof, may be effected by automatic means, such as by an air cylinder B (Figs. 14, 16 and 17) the piston of which is connected to the carriage 69 by a connecting rod 99'. The drum assembly carriage 69 is positively locked in its forward position, during the ensuing envelope bending operation, by means of a ratchet comprising a pawl I I3 on the carriage 69 which drops into a notch in a ratchet stop I I4 mounted on the upper side of the table top 40. After the drum assembly carriage 69 has been thus advanced and locked in its forward or operative position, the separated drum discs I6 are brought together to cause the gripping jaws I05 to close around the boss 8 on the lower lamp end cap I and thus firmly clamp the lower end of the envelope to the drum 61 within the groove 8| therein. The closing of the drum discs (6 is effected by releasing the catch detent I02 from engagement with the end of the bracket arm 93 and allowing the pull of the springs IOI to pivot the bell crank lever and thus actuate the slide 99, toggle links 88, and levers 84 to bring the drum discs 16 together.

The advancing movement of the drum assembly carriage 69 along the track 53 to its forward position also serves to automatically position the envelope back support 99 in proper envelope supporting position so as to prevent backward bowing of the envelope during the bending thereof. As shown particularly in Fig. 11, the envelope back support 96 comprises an asbestos covered vertically extending channel or trough coextensive with the lamp envelope 2 and having a semicircular cross section conforming to the cross sectional curvature of the lamp envelope. The back support 66 is carried by a plurality of bracket arms H5 which are mounted on and fixedly secured to a vertically extending shaft IIB extending alongside the drum 6! adjacent the forwardly facing peripheral portion thereof. The shaft H6 is J'ournalled in bearings Ill carried by brackets I I8 fastened to the guide columns 70. The bracket arms H5 also carry heating means H9 for maintaining the back support 66 in a heated condition so as not to crack the glass lamp envelope.

Transits vfor instance, disposed closely adjacent the backside of and poextensive with the back support .65. The front side I 2i of the bar I25, i. e. the side facing the back support 56, is provided with a high-resistance heating wire I122 which is wound back and forth across the said front face .I2I of the bar throughout it full verticalexl ent.

At its lower end, the shaft IIIi carries a spur gear I23 which meshes with a sector gear @I 2.4 pivotally mounted on a vertical stud I25 carried by an angular extension I26 on the lowermost bracket H8. The sector with an arm I2! extending more or less transversely of the carriage track 53 and carrying a roller I 28 at its outer end.

The sector gear I24 is normally maintained in .a retracted position .(as shown in Fig. 11) wherein the envelope back support 6.5 is swung a sufiicient distance to one side from its actualenvelope supporting position (preferably around 90 .or thereabouts) so as to clear the lamp envelope .2

during the advancing movement of the drum assembly carriage E9 to its forward position on the track 53. The sector gear I24 is normally held in such retracted position by the action of a tension coil spring I29 connected at one end to the sector gear and anchored at its other end to a stationary part of the drum assembly carriage, such as an anchor bracket I35 especially provided for such purpose. The retracted position of the sector gear I24 is determined by the engagement of a stop pin 1.3! carried by the sector gear with the extension I25 on the lower bracket II8.

During the latter part of the advancing movement of the drum assembly carriage 69 to its forward position on the track 53, the roller I28 on the sector gear I24 engages a stationary stop plate I32 fastened to the sidebar I8 of the envelope supporting framework Hi. This engagement of the roller I28 with the stop plate I32 causes the sector gear I24 to pivot and thus rotate the spur gear :I23 and its associated shaft I It so as to swing the back support 35 inwardly, around the back of the envelope 2, and position it in its envelope supporting position just as the drum assembly carriage 59 reaches its forward position on the track 513. To prevent any tendency of the sector gear I24 to pivot beyond its advanced position and thus tend to swing the back support 66 beyor d its envelope supporting position so as to strike a sudden and possibly damaging blow against the glass envelope 2, suitable stop means are provided preferably in the form of a short blank portion 124' onthe sector gear at the rear end thereof the said blank portion I24 being devoid of gear teeth. The blank portion I24 of the sector gear thus terminates rotation of the meshedlgears I24 and I23 at the point where the envelope back support is in its proper envelope supporting position.

Just as the discs I come together and the jaws I-ll5 grip the lower lamp end cap Ti following release of the disc montrol means 83, the lower ilamp holder I5 is moved downwardly out of -engagernent with the lower end of the envelope so as to clear the said lower envelope end and the drum holder jaws I55 during the ensuing envelope bending operation. This downward withdrawal of the lower lamp holder I5 is automatically produced by means of a pair of solenoids I33 and I34 (Fig. 2) mounted on :the table I! re- .gear I24 is provided 4 groove 8 I therein.

' sure of a microswitch assembly carriage spectively above and below the table top 40. The armature I35 of solenoid I33 is connected to the slide bar :62 and is arranged to pull the said bar laterally out from under the collar BI on the lower holder support rod 38 when the solenoid I 33 is energized. The armature I35 of the other solenoid I34 is connected to the lower holder sup port rod 38 "by a tie rod i3! and is arranged to exert a downward pull on the holder rod 38 when the solenoid I34 is energized. The two solenoids I33 and I34 are simultaneously energized by the closure of a microswitch I38 mounted on an upstanding bracket i39 carried by the drum assembly carriage 53. The switch I 38 is closed, during the very last part of the closing movement of the drum discs 13 and associated shafts 11, by an arm I46 carried by the outer end of one of the drum disc shafts Ti and engaging with the controlfinger I4I of the switch. Upon energization of the two solenoids I33 and I34 by the closure of switch I38, the armature I35 oi solenoid I33 first draws the slide bar 62 laterally out from under the collar 5| on the lower holder rod 38 to thereby free the lower holder I5 for additional downward movement, after which the armature I36 of the other solenoid .I 34 then pulls the holder rod 38 downwardly so .as to move the lower lamp holder I5 down to a position .(as denoted by the dotted line indication 3.6. of the collar 5!) where it will not interfere with the .drum holder jaws I05 and the lower end of the lamp envelope 2 during the ensuing bending operation.

As soon as the lower holder I5 has been thus lowered away from the lower end of the lamp envelope 2, the drum lift carriage 58 is immediately raised at a uniform rate and the drum Ii simultaneously rotated in the proper direction, at a uniform peripheral speed corresponding to the speed of upward movement of the drum, to thereby bend and wrap the lamp envelope .2 around the periphery of the drum within the The upward movement of the 68 is effected by means of an I42 which is energized by the clo- I43 (Fig. 2) mounted beneath the tabletop 40. The said switch I 43 is closed, during the latter part of the downward movement of holder rod 38 by solenoid I34 through the engagement of an arm I44 on rod 38 with the actuating button I45 of the switch I43.

The electric motor I42 for raising the drum lift carriage 68 is mounted on a platform I45 at the top of the framework II, I2 carried by the drum 7 59. The motor 142 is connected by abelt I41 to a speedreducer I48 also mounted on the frame platform M5 and having a horizontally disposed output shaft I49 extending parallel to the drum disc shafts "II. The speed reducer shaft I49 is journalled in bearings I mounted on the frame platform I46 and is provided with a pair of sprockets ISI for driving engagement with a pair of carriage-lifting roller chains I52. The said roller chains I52 are connectedat one end to the individual arms I4 of the drum lift carriage frame I3 and extend up and around the sprockets I5I and thence over a .pair of idler sprockets I53 mounted on-an idler shaft I54 journalled in bearings I55 on the platform I46. The other ends of the roller chains I52 are connected to counterweights I56 freely movable along steeply inclined guide tracks I51. The said guide tracks I151 are in the form ofibars or straps fastened at their lower ends to the drum assembly drum lift carriage electric motor 7 carriage 169 and at their upper ends to the plat- 11 form I46, the said bars I51 thus constituting part of the supporting framework for the motor support platform I46. The counterweights I56 are supported on the guide bars I51 by sets of rollers I58 which engage and freely ride along opposite sides of the guide bars I 51.

As shown in Fig. 12, the closure of switch I43 connects the solenoid R of a magnetic motor reversing switch unit I59 across the lines LI and L3 of a three-phase A. C. current supply, the circuit being completed through leads I68, I6I, I62, I63, I64, I65 and a normally closed motor shut-off microswitch I66. The resulting energization of the solenoid R closes the bank of four normally open contacts CI of the magnetic switch I59, thus connecting the motor leads I61, I68 and I69 to the three lines LI, L2 and L3, respectively, of the current source and so starting the operation of the motor. The closure of the contacts CI also serves to close a shunt circuit I 18, HI across the motor starting switch I43. The magnetic motor reversing switch unit I59 may be of a well known type manufactured commercially. In such a type switch, when one bank of contacts CI or C2 closes, the other bank is automatically maintained open.

The rotation of the drum 61, during the upward movement of the drum lift carriage 68 on guide columns 10, is produced by a separate disc rotating mechanism for each of the drum discs 16, which mechanisms rotate the two discs in unison. As shown in Fig. 1, the disc-rotating mechanisms, which are of identical characteristics, comprise a pair of vertically extending racks I12 secured at their lower ends to the drum assembly carriage 69 and at their upper ends to the motor support platform I46. The two racks I 12 extend alongside the respective arms 14 of the drum lift carriage frame 13 and are received within notches I13 (Fig. 8) in the said frame arms 14. A pair of spur gears I14, keyed to shafts I carried by the carriage frame arms 14, mesh with the teeth of the respective racks I12. Other spur gears I16 on the said shafts I15 mesh with idler gears I11 which, in turn, mesh with spur gears I18 keyed to bushings I19 (Fig. 9) on the drum disc shafts 11. The bushings I19 are keyed to, but axially slidable on the drum disc shafts 11. The idler gears I11 are rotatably mounted on shafts I80 carried by adjustable arms I8I which are pivoted on the shafts I15 and are fastened in proper position by locking bolts I82 threaded into brackets I83 depending from the carriage frame 13.

When the drum lift carriage 68 is moved vertically on the guide columns 18, the engagement of the racks I12 with gears I14 causes the gear shafts I15 to rotate. The resulting rotational movement of the said shafts I15 is then transmitted to the drum disc shafts 11, and thus to the drum discs 16 themselves, by the intermeshing gears I16, I11 and I18. As viewed in Fig. 1, the drum 61 is rotated in a counterclockwise direction when the drum lift carriage 68 is raised and in a clockwise direction when the said carriage IS lowered. The various gears I14, I16, I11 and I18 comprising the disc rotating mechanisms are so selected as to impart the desired amount of rotation (slightly less than one full revolution) to the drum 61 during the upward travel of the drum lift carriage 68.

As the drum 61 starts to rotate upon raising of the drum lift carriage 68, the arm I40 on drum the soleno1d operating switch I38, thus opening energization of solenoid I33 permits the solenoid armature I35 and thus the slide or stop 62 connected thereto, to be returned to and held in its normally out position (with the yoked end 63 of the stop 62 engaging the lower holder support rod 38) by the pull of a tension coil spring I 84 which is fastened at one end to the pin I85 connecting the armature I35 and slide 62 and anchored at its other end to a post I86 on the slide block 64. Meanwhile, the resulting simultaneous de-energization of the other solenoid I34 permits the lower holder support rod 38 to be lifted by the expansive force of a light compression coil spring I 81 mounted on the said rod and resting on the upper end of the sleeve bearing 39. The spring I 81 raises the lower holder rod 38 only a short distance just suificient to lift the switch operating arm I44 up off the switch control button I45 and open the motor starting switch I43, but not sufficient to raise the collar 6I to the level of the yoked end 63 of stop 62. Following the opening of the motor starting switch I43, the motor I42 continues to operate by virtue of the shunt circuit I10, I1I previously established across the switch I43 through closure of the bank of contacts CI by the energized solenoid R.

The upward movement of the drurn lift carriage 66 by the motor I42 continues until the envelope 2 has been completely bent or wrapped around the periphery of the drum 61 at which time the upward movement of the drum lift carriage 68 is terminated by the engagement of the carriage frame bushings 15 with upper stops I88 on the guide columns 19. However, just before the bushings 15 strike against the said stops I88, the electric motor I42 is de-energized by the opening of the switch I 66 which is mounted on a vertically extending bar I89 carried by the drum assembly carriage 69. The switch I 66 is opened by a wiper arm I98 which is carried by the drum lift carriage 68 and engages the control button I 9I of the switch near the end of the upward movement of the said carriage 68. The wiper arm I 96 is fastened to the outer end of one of the idler gear shafts I88. The opening of switch I66 interrupts the circuit through the solenoid R. of the magnetic switch unit I59 thus de-energizing the said solenoid R and so permitting the bank of contacts CI to open and so interrupt the motor current supply. The rotational inertia of the motor I42, following its de-energization by the opening of switch I66, carries the drum lift carriage 68 the remainiing short distance upward to its uppermost position against the stops I88 before rotation of the motor actually stops. An electromagnetic brake I92 (Fig. 1) on the motor I42 effectively brakes and abruptly arrests the rotation of the motor shaft following the opening of the motor shut-off switch I66 and the de-energization of the motor.

In order that the envelope 2 possess the same cross-sectional shape after bending as it originally possessed, a gaseous pressure sufiiciently above atmospheric is created within the envelope while the latter is still in a plastic condition. This gaseous pressure may be created at the very outset of, or at some time during the actual envelope bending operation and continued up until the end of such bending operation; or it may be created instead at the end of the envelope bending operation, or even after the end of such operation providing the envelope is still in a plastic condition. Preferably, however, the said gaseous pressure is created just as the bending of the envelope '2 is being completed, and is efiected by increasing the pressure of the nitrogen or other inert gas flowing into the lamp envelope to an amount (for instance 3 to 6 inches, or so, head of mercury) sufficient to expand the plastic wall of the envelope :to its original cross-sectional shape. Prior to such gas .pressure increase, the flow :of inert gas through the lamp envelope 2 is maintained at a relatively slight pressure, for instance at inch, or so, head of water, by means of a valve or stop .cock 193 (Fig. 13) which is connected in a bleeder line .194 and is so adjusted as to bleed the desired amount of inert gas into the envelope 2. The subsequent increase in the pressure of the inert gas within the envelope 2 may be produced by the opening of a normally closed solenoid valve '195 which is connected in a bypass line 196 connected around the bleeder line 194. The opening of the solenoid valve 195 is controlled by a normally open microswitch 191 which is mounted on the bar 189 in such a position as to be closed, by the engagement of the switch control finger 98 with the wiper arm 199, preferably -just before the carriage 68 reaches its uppermost position. Upon opening of the solenoid valve 195, the flow of inert gas through the by-pass line 196 is thus added to the how of inert gas through the bleeder-line 194. A suitable pressure relief valve 199, connected in the by-pass line 196, controls the flow of inert gas through the by-pass line so that the combined flow of gas from the two lines 194, 1196 will be at the desired pressure of from 3 to 4 inches head of mercury.

After the drum lift carriage 68 reaches its uppermost position and while it is held in such position by the counter-weights 156, a temporary support 299 (Fig. 2) is positioned beneath and in engagement with the circularly bent lamp envelope 2 (as shown in dotted lines in Fig. 1) after which the two drum discs 16 are separated by operation of the disc control means -83 and the drumassembly carriage -69 then retracted or withdrawn along the track 59 to thereby dissociate the circular lamp assembly from the drum -61 and thus permit its removal from the upper lamp holder '14. The temporary envelope support 200 may comprise a V-block 291 fastened to one end of a lever 292 pivotally mounted on a bracket293 fastened to one of the side bars 18 of the framework 16. Suitable'locking means, such as a spring operated pin 294 mounted on the lever 292 and fitting into a slot 295 in thebracket 2113,, are provided for locking the envelope support .200 in proper envelope supporting position. The lever 292 .may be provided with a handle .296 for swinging the envelopesupport to its envelope supporting position.

During the withdrawal movement of the drum assembly carriageBBalong the track 53, the :front bar .291 of the said carriage strikes against the control button .298 of a normally open motor restart microswitch 299 mounted ona bracket 2.159 extending from the track 1153. Asshown in Fig, 12, the closure of switch 299 connects .the solenoid F of the magnetic switch unit 159 across the lines L1 and L3 of the current supply, the circuit being completed through leads 169, 21 I, .212, 2.1.3, 214, 1:65 .and a normally closed motor stop switch 215. The resulting energization of the solenoid F ,closes the bank of four normally open contacts C2of the magneticswitch unit 159, .thus connecting themotor leads 191. 1-69 and 169 respectively to .lines L3, L2, L1 or the current operating slide 99.

supply and restarting the motor. However, because .of the reversal of the connection of motor leads 16 1., 199 to lines L1, L3 from their previous connection through the contacts C1, the motor operates in a reverse direction so as to lower the drum jlift carriage 68 on the guide columns 19. In addition'to restarting the motor 142 in a reverse direction, the closure of the bank of .contacts C2 also closes a shunt circuit 216 across the motor restarting switch 209.

The lowering .of the drum lift carriage :98 by the motor 142 continues until the bushings "15 on the carriage frame 19 strike against the lower stops H11 on the guide column .19, thus positioning the carriage 98 once again in its lowered or starting position preparatory to the bending of the next lamp envelope assembly 1'. .Just before the carriage 68 reaches its lowered position, however, the wiper arm 149 on the carriage engages the control button 211 of, and-opens the motor ,stop switch 215 mounted on the bar 189. lhe

opening of the said switch 215 breaks the bir- :cuit through the solenoid F of the magnetic switch unit 159, thus opening the bank of :contacts C2 and interrupting the motor current supply circuit. As in the case of the upward move- .ment of the carriage 98, the rotational inertia of the motor 142, following its de-energ-ization, lowers the drum lift carriage -,68 the remaining short distance down to its starting position against the lower stops 111 before rotation of the motor is actually stopped by the electromagnetic brake I92 thereon. After the return of the carriage 68 to its lowered position, the lower lamp holder 15 ,is then manually reset, by withdrawing the stop .62 and lifting the collar 61 .on rod 39 up past the yokedcnd 93 of the said stop, to again place the apparatus in condition for the next envelope bending operation.

Figs. 14 and 15 illustrate a modification of the invention wherein the drum discs 16 are automatically closed or moved together just as the to thereby close the discs '16 together and thus {clamp the lower end of the lamp envelope 2 to the drum periphery. As shown, the said release means 218 comprises arelease pin 219 vertically .reciprocable in the bracket 94 and. projecting upwardly through a slot 229 in the drum disc At its upper end, the pin 21.9;is provided with a head portion 221 which is receivable within a correspondingly shaped recess .222 (Fig. 15) in the upper side of the slide 99 to thereby lock the slide in its retracted or disc-separated position. The pin 219 is normally maintained in a lowered position, with its head portion 221 received within the slide recess 222, by the expensive force of a compression coil spring 223 mounted on the pin and compressed between the upper bracket arm 93 and ,a .collar .224 fastened on the pin.

Mounted beneath and in vertical alignment with the release pin 219 is a push rod 225 vertically reciprocable in a bushing 2.29 mounted on the drum assembly carriage '69. The push rod 225 is normally maintained in a lowered position slightly spaced from the release pin 219, as de .termined by the engagement of a collar 2.21 on the said-rod with the upper end :of bushing .226, by the expansive action of a compression coil l spring 228 mounted on the rod within the bushing 226 and compressed between shoulders on the said bushing and rod. When the drum assembly carriage 69 is located in its forward or envelope bending position as shown in Fig. 14, the push rod 225 is positioned over and in vertical alignment with the plunger 229 of a solenoid 23%] mounted beneath the table top til. The said plunger 229 projects upwardly through the table top and is normally held in a lowered position, slightly spaced from the push rod 225, by the pull of a spring 23i acting through a lever 232 connected to the plunger.

Just as the drum assembly carriage 69 reaches its advanced or envelope bending position on the track 53, the solenoid 230 is energized by the closure of a microswitch 233 carried by a bracket 234 mounted on the table H, the switch 233 being closed by the engagement of the front cross bar 201 of the carriage with the button 235 of the switch. The energization of the solenoid 238' raises the plunger 229 which then raises, in turn, the push rod 225 and the release pin 2E9 so as to lift the head 22E of the release pin out of the recess 222 in slide 98 (as shown in dotted lines in Fig. 14) and thus free the said slide for forward movement. The pull of the springs IUI then pivots the bell crank lever 95 to advance the slide 90 so as to effect the closure of the drum discs 16.

Figs. 16 and 1'? illustrate a modified form of envelope heating furnace 236 which automatically opens and closes, during the movement of the furnace carriage 52 along the track 53, to allow entry and withdrawal of the lamp assembly I. As shown, the furnace 235 is divided, in a vertical plane paralleling the track 53, into two complementary swinging sections 23?, 235 respectively supported on vertically extending rotatable shafts 238, 238 by means of brackets 239 pinned or otherwise secured to the said shafts so as to rotate therewith. The shafts 238 are located adjacent the rear side of the furnace 236 and are journalled at their upper and lower ends in suitable bearings carried by upper and lower cross 'bars 240 and 2 3i of the furnace carriage frame.

At their lower ends, the shafts 238 are provided with cam follower arms 242, 2 22 carrying rollers 243 which ride in separate cam tracks 2%, 2 34 in a horizontally disposed cam plate 265. The cam plate 245 is suitably supported on the table I! in a position below the level of the furnace carriage frame cross bars 2M and 246 so as to clear the said cross bars during movement of the carriage 52 along the track 53. The rollers 2 33, riding in the cam tracks 2 34 during movement of the furnace carriage 52 along the track 53, cause the follower arms 242 to swing and thus rotate the vertical shafts 233 so as to swing open or closed the furnace sections 23?. The cam tracks 254 are so shaped as to swing the furnace sections 237 open (as shown in dotted lines in Fig. 16) during the very first part of the advance movement of the furnace carriage 52 along track 53 to its envelope heating position, and to then maintain the said furnace'sections open until just before they are positioned abreast of the lamp assembly I whence they are finally closed around the lamp assembly during the very last portion of the carriage advance movement.

As shown in Fig. 16, when the furnace 235 is positioned in its envelope heating position with the sections thereof closed around the lamp envelope 2, the said envelope is preferably located in a position offset a slight distance rearwardly from the axis of the heating circle 24'. defined by the inner cross sectional surface of the furnace so that the back side of the envelope (i. e., the side that is to form the outside of the circularly bent envelope and therefore has to stretch the most) receives a slightly greater amount of heating than the front side of the envelope. The same is true of the furnace 45 in Figs. 1 and 2.

The completed lamp may be provided with a base of the type shown in Patent 2,339,166, W. Harrison, with the base actually clamped to the peripheries of the end caps T, or to the bosses 8 thereon.

Certain features of the apparatus herein disclosed, such as the separable forming drum or mold 8?, are described and claimed in co-pending application Serial No. 534,536, A. Greiner, filed April 27, 1944 and assigned to the same assignee as this application.

What we claim as new and desire to secure by Letters Patent of the United States is:

l. The method of bending into arcuate shape a length of glass tube which comprises, heating the tube to a plastic condition extending from end to end, attaching one end of the plastic tube to the periphery of a forming mold, and then wrapping the tube around the periphery of the mold by rolling the mold along the tube.

2. The method of bending into arcuate shape a length of glass tube which comprises, heating the tube to a plastic condition extending from end to end, attaching one end of the plastic tube to the periphery of a forming mold, wrapping the tube around the periphery of the mold by rolling the mold along the tube, and preserving the original cross section of the tube by creating a gaseous pressure above atmospheric within the plastic tube.

3. The method of bending into arcuate shape a length of glass tube which comprises, heating the tube to a plastic condition extending from end to end, attaching one end of the plastic tube to the periphery of a forming mold, wrapping the tube around the periphery of the mold by rolling the mold along the tube, and preserving the original cross section of the tube by creating a gaseous pressure above atmospheric within the plastic tube approximately at the end of the bending operation.

4. The method of bending into arcuate shape a length of glass tube which comprises, supporting the tube in a vertical position, heating the tube to a plastic condition extending from end to end, attaching the lower end of the plastic tube to the periphery of a forming mold, and then wrapping the tube around the periphery of the mold by rolling the mold up along the tube.

5. The method of bending into arcuate shape a length of glass tube having end caps secured to its opposite ends which method comprises, supporting the tube by its end caps, heating the tube to a plastic condition extending from end to end, attaching the end cap at one end of the tube to the periphery of a forming mold, and then wrapping the tube around the periphery of the mold by rolling the mold along the tube.

6. The method of bending into arcuate shape a tubular electric discharge lamp having a coating of fluorescent material on the inner wall of the glass lamp envelope and end caps secured to its opposite ends which method comprises, supporting the lamp by its end caps, creating an atmosphere of inert gas at a slight pressure within the lamp, heating the glass lamp envelope to a plastic condition extending from end to end,

attaching the end cap at one end of the lamp to the periphery of a forming mold, wrapping the lamp around the periphery of the mold by rolling the mold along the lamp, and increasing the pressure of the inert gas within the lamp approximately at the end of the bending operation to expand and restore to original cross-sectional shape those portions of the glass envelope which may have partially collapsed during the wrapping of the lamp around the mold.

7. The method of bending into arcuate shape a length of glass tube which comprises, heating the tube to a plastic condition extending from end to end, attaching one end of the plastic tube tangentially to and within an annular groove in the periphery of a rotatable drum axially separable at said groove into two sections, Wrapping the tube around the periphery of the drum by rolling the drum along the tube, and separating said drum at the groove therein to dissociate the bent tube from the drum. i

8. The method of bending a length of glass tube into arcuate shape which comprises, holding the tube by its upper end in a vertical position so that it is free to elongate, heatin the tube to a plastic condition and, upon elongation of the tube to a predetermined length, bending the tube into arcuate shape.

9. Apparatus for bending into arcuate shape a length or glass tube heated to a plastic condition,

said apparatus comprising means for supporting the tube, a rotatable and movable inold arranged to be located adjacent one end of the tube with the tube tangent thereto, means for attaching said one end of the tube to the periphery of the mold, means for simultaneously rotatingthe mold and moving it bodily in a direction longitudinally of the tube to cause the tube to be wrapped around the periphery of the mold, and control means actuated by attachment of the tube to the i mold to set in operation the last-named means.

10. Apparatus for bending into arcuate shape a length of glass tube heated to a plastic condition, said apparatus comprising means tor supporting the tube, a rotatable and movable mold arranged to be located adjacent one end of the tube with the tube tangent thereto, means for securing said one end of the tube to the periphery of the mold, means for simultaneously rotating lthe mold and moving it bodily in a direction longitudinally of the tube to cause the tube to be wrapped around the peripheryof the mold, and means for creating a gaseous pressure above atmospheric within the plastic tube while itis on the mold to preserve its original cross-sectional shape.

11. Apparatus for bending into arcuate shape a length of glass tube heated to .a plastic condition, said apparatus comprising means for supporting the tube, a rotatable and movable mold arranged to be located adjacent one end of the tube with the tube tangent thereto, means for securing said one end of the tube to the periphery of the mold, means for simultaneously rotating the mold and moving its bodily ,in a direction longitudinally of the tube to cause the tube to be wrapped around the periphery of the mold, means for creating a gaseous pressure above atmospheric within the plastic tube while it is on the mold to restore its original cross-sectional shape, and control means actuated by movement of saidmold to render the last-named means operative approximately at the end of the tube bending operation. i

12. Apparatus for bending into arcuate-shape alength of glass tube comprising means for sup-- porting the tube, means in operative relation to said tube supporting means for heating the tube to approximately uniform plastic condition around its full circumferential extent and throughout its entire length, a rotatable and movable forming drum arranged to be located adjacent one end of the tube with the tube tangent thereto and having an annular tube receiving groove in its periphery and axially separable at Said groove into two sections, means for securing said one end of the tube to the periphery of the drum within the groove therein, and means for simultaneously rotating the drum and moving it bodily in a direction longitudinally of the tube to cause the tube to be wrapped around the periphery of the drum within the groove therein.

13. Apparatus for bending into arcuate shape a length of glass tube heated to a plastic condition, said apparatus comprising means for supporting the tube from its upper end in a vertical position, a rotatable and movable mold arranged to be located at the lower end of the tube with the tube tangent thereto, means for securing the lower end of the tube to the periphery of the mold, and means for simultaneously rotating the mold and moving it bodily upwardly along the tube to cause the tube .to be wrapped around the periphery of the mold.

14. Apparatus for bending into arcuateshape a length of glass tube comprising means for supporting the tube including a back support arranged to extend along one side thereof, means in operative relation to said tube supporting means for heating the tube to approximately uniform plastic condition around its full circumferential extent and throughout its entire length, a rotatable and movable mold arranged to engage with the other side of the tube and to be located at one end of the tube with the tube tangent thereto, means for securing said one ender the tube to the periphery of the mold, and for simultaneously rotating the mold moving it bodily in a direction longitudinally of the tube to cause the tube to be wrapped around the periphery of the mold.

15. Apparatus for bending a length of glass tube into arcuate shape comprising, means for supporting the tube in a vertical position and fixedl holding it by its upper end so that it is free to elongate in a downward direction, means in operative relation to said tube supporting means for heating the tube to a plastic condition while so supported, stop means in alignment with said tube supporting means for limiting elongation of the tube during heating to a predetermined length, a rotatable and movable mold arranged to be located adjacent the lower end of said tube with the tube tangent thereto, means for fixedly securing one end of the tube to the periphery of the mold, and means for simultaneously rotating the mold and moving it bodily vertically along the tube to cause the tube to be wrapped around the periphery of the mold.

16. Apparatus for bending into arcuate shape a length of glass tube heated to a plastic condition, said apparatus comprising means for supporting the tube and including a movable holder engaging one end of the tube, a rotatable and movable mold arranged to be located adjacent thesaidlend of the .tube with the tube tangent thereto, means for attaching the said one end of 'the tube to the periphery of the mold, means for disengaging and withdrawing said holder away from said tube end, control means to eiTect operation of the last-named means, means operable upon attachment of the tube to the mold to actuate the said control means, and means for simultaneously rotating the mold and moving it bodily in a direction longitudinally of the tube to cause the tube to be wrapped around the periphcry of the mold.

17. Apparatus for bending into arcuate shape a length of glass tube heated to a plastic condition, said apparatus comprising means for supporting the tube and including a holder engaging one end of the tube, a rotatable and movable forming drum arranged to be located adjacent the said end of the tube with the tube tangent thereto and having an annular tube-receiving groove in its periphery and axially separable at said groove into two sections, means normally holding said drum sections separated, means for closing said drum sections, means on said drum for attaching the said one end of the tube to the periphery of the drum upon closure of the drum sections, means for disengaging and withdrawing said holder away from said tube end, control means operated by closure of the drum sections to actuate the last-named means, means for rotating the drum and moving it bodily along the tube to cause the tube to be wrapped around the periphery of the drum and control means operated by withdrawal of said holder to set in operation the last-named means.

18. Apparatus for bending into arcuate shape a length of glass tube heated to a plastic condition, said apparatus comprising means for supporting the tube, a rotatable forming drum arranged to be located adjacent one end of the tube with the tube tangent thereto and having an annular tube-receiving groove in its periphery and axially separable at said groove into two sections, means normally holding said drum sections separated, a carriage for said drum movable to advance the drum into and out of tube bending position, means for automatically closing the drum sections together, control means operated by the advance movement of the carriage to effect operation of the last-named drum closing means, means for securing one end of the tube to the periphery of the drum within the groove therein, and means for rotating the drum and moving it bodily along the tube to cause the tube to be wrapped around the periphery of the drum Within the groove therein.

19. Apparatus for bending a length of glass tube into arcuate shape comprising, means for supporting said tube, an oven arranged to be 10- cated in operative relation to a tube in said supporting means for heating said tube to a plastic condition, an oven carrier movable to advance said oven into and out of tube heating position, a carriage mounted for movement longitudinally of the tube, a forming mold rotatably mounted on said carriage and arranged to be located adjacent one end of the tube with the tube tangent thereto, a carrier for the mold carriage mounted for movement to advance the mold into and out of tube bending position, means on said mold for securing said one end of the tube to the periphery of the mold, and means for rotating the mold during movement of the carriage longitudinally of the tube to thereby cause the tube to be wrapped around the periphery of the mold.

20. Apparatus for bending a length of glass tube into arcuate shape comprising, means for supporting said tube in a vertical position, an oven arranged to be located in operative relation to a tube in said supporting means for heating said tube to a plastic condition, a horizontally extending track under said tube supporting means, a carrier for said oven mounted for movement along said track to advance the oven into and out of tube heating position, a vertically eX- tending second carrier mounted for movement along said track, a carriage slidably mounted on said second carrier for vertical movement thereon, a forming mold rotatably mounted on said carriage and movable into and out of the tube bending position adjacent the lower end of the tube with the tube tangent thereto by movement of said second carrier along the track, means on said mold for securing the lower end of the tube to the peripher of the mold, and means on said second carrier for rotating said mold during upward movement of the carriage on said second carrier to thereby cause the tube to be Wrapped around the periphery of the mold.

21. The method of bending a length of glass tube into arcuate shape which comprises fusing metal end caps to the opposite ends of the tube, supporting the tube in a vertical position by gripping the end cap at the upper end thereof, heating the tube to a plastic condition, clamping the lower end of the tube to a point on the periphery of a forming mold by gripping the lower end cap, and then wrapping the tube around the mold by rolling the mold up along the tube.

22. In apparatus for bending a length of glass tube into arcuate shape, the combination of means for supporting the tube in a vertical position and fixedly holding it by its upper end so that it is free to elongate in a downward direction when heated, means in operative relation to said tube supporting means for heating the tube to a plastic condition, means for controlling elongation of the tube to a predetermined length, and means for thereafter bending the tube into arouate shape.

23. The method of forming a length of glass tube into a coil which comprises preliminarily heating the tube to a plastic condition and stretching it to a predetermined length, and then bending it into coil form.

24. The method of forming a, length of glass tube into a coil which comprises preliminarily heating the tube to a plastic condition and stretching it to a predetermined length, and then bending it into coil form by attaching one end of the tube to the periphery of a mold of a predetermined diameter and a circumference slightly larger than the said predetermined length of the tube and then wrapping the tube around the mold to form a coil having its ends spaced apart a definite predetermined distance.

25. The method of coiling a length of glass tube which comprises preliminarily fusing metal end caps to the opposite ends of the tube, suspending the tube in a vertical position by gripping the cap at the upper end thereof and heating the suspended tube to a plastic condition, and then gripping the cap at the lower end and bending the tube into a coil.

26. The method of coiling a length of glass tube which comprises preliminarily fusing metal end caps to the opposite ends ofthe tube, suspending the tube in a vertical position by gripping the cap at the upper end thereof and heating the suspended tube to a plastic condition for a time sufficient to stretch it to a predetermined length, and then gripping the cap at the lower end and bending the tube into a coil.

27. Apparatus for coiling glass tube comprising means for heating the tube to a plastic condition, means for supporting the tube in operative relation to said heating means in a manner to cause the tube to be stretched to a predetermined length, and means for thereafter coiling the plastic tube.

28. Apparatus for coiling glass tube comprising means for heating the tube to a plastic condition, means for supporting the tube in operative relation to said heating means in a manner to cause the tube to be stretched to a predetermined length, a rotatable mold arranged to be located adjacent one end of the tube with the tube tangent thereto, clamp means on said mold for gripping said one end of the tube, and means for rotating the mold to cause the tube to be wrapped around its periphery.

29. Apparatus for coiling glass tube comprising means for heating the tube to a plastic condition, means for suspending the tube in a vertical position from its upper end in operative relation to said heating means in a manner to cause the tube to be stretched to a predetermined length, and means for thereafter coiling the plastic tube.

30. Apparatus for coiling glass tube comprising means for heating the tube to a plastic condition,

means for suspending the tube in a vertical position from its upper end in operative relation to said heating means in a manner to cause the tube to be stretched to a predetermined length, stop means in vertical alignment with said tube supporting means and spaced therefrom a predetermined distance to limit stretching of the tube, and means for thereafter coiling the plastic tube.

ALFRED GREINER. AUGUST W. SEI'IZ.

REFERENCES CITED The following references are of record. in the file of this patent:

UNITED STATES PATENTS 

